Balancing and control devices for hydraulic circuits

ABSTRACT

A balancing and control device, for use in a hydraulic circuit, which can be adjusted to compensate for loss of hydraulic fluid by leakage, evaporation etc. The device comprises a casing which, together with a diaphragm, forms an enclosure. The enclosure is connected to a hydraulic circuit. The position of the diaphragm and thus the volume of the enclosure is adjustable by adjusting screw means against which the diaphragm is urged by spring means.

United States Patent lnventor Jules Antonin Sombardier Pau, France Appl.No. 725,305

Filed Apr. 30, 1968 Patented Feb. 16, 1971 Assignee Societe dite:Projecteurs Cibie Bobigny (Seine St.-Denis), France a company of FrancePriority May 3, 1967 France 105,165

BALANCING AND CONTROL DEVICES FOR HYDRAULIC CIRCUITS 3 Claims, 2 DrawingFigs.

US. Cl 138/30; 1 3 7/593 Int. Cl F161 55/04 Field of Search 138/30;

[56] References Cited UNITED STATES PATENTS 1,765,930 6/1930 McGonegal138/30 2,893,434 7/1959 Ballard 138/30 3,130,751 4/1964 Lapas 138/303,237,715 3/1966 Peters 138/30X 3,366,144 1/1968 Durst 138/30 PrimaryExaminerHerbert F. Ross Attorney-Ward, Mc Elhannon, Brooks & FitzpatrickABSTRACT: A balancing and control device, for use in a hydrauliccircuit, which can be adjusted to compensate for loss of hydraulic fluidby leakage, evaporation etc. The device comprises a casing which,together with a diaphragm, forms an enclosure. The enclosure isconnected to a hydraulic circuit. The position of the diaphragm and thusthe volume of the enclosure is adjustable by adjusting; screw meansagainst which the diaphragm is urged by spring means.

PATENTEU FEB] 5197:

BALANCING AND CONTROL DEVICES FOR HYDRAULIC CIRCUITS The presentinvention relates to a balancing and control device for hydrauliccircuits. 7

Hydraulic control circuits are in widespread use in technology, for thepurpose of transmitting a motion or a displacement from a controlelement to a controlled element. In particular, systems for automaticadjustment of the orientation of the headlights of a self-propelledvehicle as a function of its positioning are already known, in which therelative motion between the sprung and unsprung portions of the vehicleis transmitted to the headlights to adjust their direction aroundhorizontal axes, in other words their vertical orientation.

Systems of this nature have been described, for example, in the FrenchPat. Nos. 1,358,632, 1,409,173, 1,438,576, 1,458,674, owned by theapplicants.

In many instances, and specifically for the systems for directionalcontrol over the headlights of vehicles, the hydraulic circuit should beparticularly precise in action, that is to say that the appropriatecorrespondence established initially between the orientation of theheadlights and the riding position of the vehicle, remains appropriatelyconstant in the long run, without accidental maladjustment. In practice,it has been noted that even when employing closed andfundamentallysealed hydraulic circuits, leaks, seepage and evaporation intervened attimes, causing a reduction in the quantity of liquid of the circuits,thereby progressively diminishing the precision of the control. Theprecision of the control is also affected by temperature changes.

The present invention has the object ofeliminating these shortcomings,and to this end it relates to,a balancing device intended to beconnected to a' hydraulic circuit to allow the volume of the enclosurecontaining the hydraulic transmission liquid to be compensatorily variedunder the action of a control element operated manually orautomatically. A device of this nature may compensory installed inseries with the hydraulic circuit, that is to say between the controlelement and the controlled element, or in parallel with the same.

The present invention consists in abalancing device for a hydrauliccircuit comprising a casing having a diaphragm which completes a sealedenclosure withinthe casing, said enclosure being adapted to be connectedto a hydraulic circuit, the position of the diaphragm and thus thevolume of the enclosure being adjustable by adjusting screw meansagainst which the diaphragm is urged by spring means.

Preferably, the adjusting screw means is engaged in a thread borne bythe casing.

The screwthread maybe that of a nut secured immovably on the side of thecase. In more highlydeveloped forms of embodiment, the nut is arrangedto slide at right angles to the diaphragm, the loading spring alwaystending to thrust the screwnut combination back until a peripheralshoulder or step of the nut comes into abutment against the internalsurface of the case. In these circumstances, screwing the adjustingscrew in the nut allows of precise adjustment of the compensatorydevice, whereas the displacement of the screwnut aggregate may beexploited to control the hydraulic circuit. The device according to theinvention may thus be considered as a device for control of thehydraulic circuit, 'with an incorporated adjusting system.

In the accompanying drawings:

FIG. I is a diagrammatical illustration in section of a compensatorydevice according to the invention, showing a first form of embodimentintended for compensory adjustment only.

FIG. 1. a illustrates a second form of embodiment of a device accordingto the invention, organized for control and corn pensatory adjustment.

ln carrying the invention into effect according to one convenient mode,by way of example, the device of FIG. 1 comprises, a case formed by twosemihousings 1 and 2 joined together by means of two peripheral flanges1a, 2a. Between the two flanges la and 2a is gripped a diaphragm 3,which is pliable and hermetic. The semihousing l and the diaphragm 3thus define an enclosure 4, of variable volume, which may be placed incommunication with the hydraulic circuit which is to be kept in a stateof balance. In the example illustrated, the enclosure 4 is shown inseries in the hydraulic circuit with an inlet lb. and outlet 1c. Theenclosure 4 could however be tapped into the circuit by means of asingle communicating orifice. I

In opposition to the diaphragm 3, the semihousing 2 has an opening 2a inwhich is installed a nut 6 having a step or shoulder 6a adapted to bearagainst the inner side of the case 2,around the entire opening 2a..lnthe shoulder 61: of the nut are formed at least two guide drillings 6bparallel to the axis of the nut which mate with guiding pins or studs 7secured to the case 2. The nut 6 may thus displaced parallel to its axisand at right angles to the diaphragm 3 towards the inside of the casebut is restricted from rotation about. its axis. Many other conventionalguiding systems could evidently endow the nut 6 with an analogous degreeof freedom.

An adjusting screw 8 having a knurled head 8a external to the case,operates in conjunction with the nut 6. A spring 9 having one endbearing against the side of the semihousing l opposite to the diaphragm3 and the other end against a thrust plate 10 linked to the diaphragm,always tends to thrust the diaphragm 3 against the extremity 8b of thescrew 8 through a counterplate 11, this counterplate contingently beingcentrally equipped with a circular rim or flange 11a employed to guidethe extremity 8b of the screw. Finally, a flexible blade 12 is fastenedon the semihousing 2 and its extremity 12a exerts retaining pressure onthe knurled head 8a.

The operation of the device is as follows. The enclosure 4 isincorporated in the hydraulic circuit which is to be kept in a state ofbalance as specified above. The spring 9 thrusts the diaphragm 3 againstthe screw 8 and by means of the screw holds the nut 6 against the innerside of the semihousing 2, and this irrespective of the d epth ofengagement of the nut 6 on the screw 8. The volume of the enclosure 4 iscaused to vary by screwing the screw 8 into or out of the nut 6 to agreater or lesser degree, in order to effect appropriate adjustment ofthe orientation of the headlights coordinated with the device of theinvention and controlled by means of the said hydraulic circuit. Also,in case of malfunction owing to a reduction in the quantity of liquidcontained in the circuit by leakage or evaporation, or else to a localor overall change in temperature in the circuit, renewed adjustment bymeans of the screw 8 renders it possible to balance this reduction.

It will be realized that in such a compensatory application of thedevice according to the invention, the possibility of sliding the nut 6relative to the case has not been exploited. The nut 6 could well befixed to the case, or may be formed by a female screwthread solidarywith the latter.

The said possibility may be exploited in another form of application ofthe device according to the invention in which the said device isexploited as a controlling and adjusting element.

A mode of operation of this nature is illustrated in FIG. 2.

The device of FIG. 2 is analogous to that of FIG. 1, and as acomplementary element, comprises a lever 13 arranged pivotally on theextremity 14a of a bearer or bracket 14 fastened on the semihousing 2.This lever comprises three arms 13a, 13b, 13c. The extremity of the arm13a bears against the knurled head 8a of the screw 8. The extremity ofthe lever 13b rests in adjusting abutment against the outer surface ofthe semihousing 2 withintercalation of an adjusting screw 15. Theextremity of the arm 13c is linked elastically by a damping spring 16 toa control rod or cable 17.

The operation of a device of this kind, when employed for compensatorypurposes, is the same as that set forth in respect of that of FIG. 1:compensatory adjustment is effected by displacing the screw 8 withrespect to the nut 6, the latter remaining stationary, the extremity ofthe arm 13a of the lever 13 remaining in contact with the head 8a of thescrew 8, under the action of the spring 16 tending to pivot the lever 13as a whole around the pivot pin 14a. In the position illustrated in FIG.2 (shoulder 6a of the nut 6 in contact with the side of the semihousing2), the headlights controlled by the hydraulic circuit occupy a certainsetting, for example, the high position. To move the headlights to theother setting (low position), the driver causes the lever 13 to pivotaround 14a by acting on the pull l7. ln this movement, the extremity ofthe arm 13a exerts a guided thrust on the screw 8 and the nut 6, causinga displacement of the diaphragm and a change in the volume of theenclosure 4. This change in volume is calculated to cause the requiredchange in the orientation of the headlights. The limit of the controlstroke between the two setting positions defined in the preceding, isestablished by the extremity 15a of the screw 15 coming into contactwith the side of the semihousing 2.

The pull 17 is connected to the dashboard of the vehicle, in a suitableand conventional manner. It will be realized that although the device ofHO. 2 has been described as a control device for setting between twopositions (a high" position,

and a low position), it may equally be arranged as a continuouslyoperating device. This possibility is particularly advantageous if theinclination of the headlights is to be adjusted progressively accordingto the load of the vehicle.

The invention is evidently not limited to the particular forms ofembodiment described and covers all modified forms within its scope. lnparticular, the control element coordinated with the device of FIG. 1 toconvert the same, as illustrated in F IG. 2, into a controllingbalancing or compensatory device, may be another element than a pivotinglever, although the latter represents a preferred feature. A pivotinglever need not necessarily comprise three branches: branch 13b could beomitted and replaced by another thrust or abutment element, for exampleone solidary with the nut 6. Finally, the pull 17 could be actuateddirect by the relative displacements between the sprung and unsprungportions of the vehicle, to cause direct and automatic variation in theorientation of the headlights as a function of the riding position of thvehicle. 1

lclaim:

l. A balancing devicefor an hydraulic system which comprises:

a casing;

a diaphragm mounted in said casing which completes a sealed enclosurewithin said casing, said enclosure being adapted to be connected to anhydraulic circuit;

a spring disposed within said enclosure urging said diaphragm toincrease the volume of said enclosure;

said casing having elongated slide guide means extending normal to saiddiaphragm,

adjusting means adapted to bear against said diaphragm in opposition tosaid spring means, said adjusting means comprising a screw threadablyengaging a nut in said casing, said nut being in casing slidably securedon said guide means for movement and in the direction of the center ofsaid diaphragm, the arrangement being such that the nut is preventedfrom rotation with respect to said casing and is held in position underthe pressure of said spring means acting on said adjusting means wherebythe volume of said enclosure may be adjusted by rotational displacementof said adjusting means and by sliding displacement of said nut.

2. The device claimed in claim 1 wherein said spring means and saidadjusting means bear against said diaphragm through guiding and abutmentelements.

3. The device of claim 2 further including a control element engagingsaid adjusting means and adapted to initiate a predetermined slidingdisplacement of said adjusting means whereby the volume of saidenclosure may be varied by a predetermined amount.

1. A balancing device for an hydraulic system which comprises: a casing;a diaphragm mounted in said casing which completes a sealed enclosurewithin said casing, said enclosure being adapted to be connected to anhydraulic circuit; a spring disposed within said enclosure urging saiddiaphragm to increase the volume of said enclosure; said casing havingelongated slide guide means extending normal to said diaphragm,adjusting means adapted to bear against said diaphragm in opposition tosaid spring means, said adjusting means comprising a screw threadablyengaging a nut in said casing, said nut being in casing slidably securedon said guide means for movement and in the direction of the center ofsaid diaphragm, the arrangement being such that the nut is preventedfrom rotation with respect to said casing and is held in position underthe pressure of said spring means acting on said adjusting means wherebythe volume of said enclosure may be adjusted by rotational displacementof said adjusting means and by sliding displacement of said nut.
 2. Thedevice claimed in claim 1 wherein said spring means and said adjustingmeans bear against said diaphragm through guiding and abutment elements.3. The device of claim 2 further including a control element engagingsaid adjusting means and adapted to initiate a predetermined slidingdisplacement of said adjusting means whereby the volume of saidenclosure may be varied by a predetermined amount.